1. Field of the Invention
The present invention is directed to a method and system of diesel engine setpoint compensation for transient operation of a heavy duty diesel engine.
2. Description of the Related Art
Sun et al, U.S. Pat. No. 6,866,030 is directed to a method for controlling a compression ignition internal combustion engine exhaust recirculation (EGR) system having an EGR valve and an actuator. The method includes continuously monitoring at least one engine parameter in real time, and continuously adjusting as EGR valve position using a control signal in real time in response to the at least one parameter and in response to at least one delay, wherein one of the at least one delays corresponds to as EGR actuator delay.
Sun, U.S. Pat. No. 7,063,076 is directed to a method of smoke limiting of an engine. The method may include determining a minimum air/fuel (AFR) ratio and fuel limiting as a function thereof. The method may further include determining a maximum fueling rate as a function of minimum AFR and sir mass flow to the engine. The method may include controlling the engine according to a requested fueling rate unless the requested fueling rate is greater than the maximum allowable fueling rate.
Diesel engines require almost constant modulation of setpoints based upon engine operating conditions. During transient engine operation (i.e. dynamic or time varying) the response time of individual engine systems must be taken into account in specifying performance setpoints. Individual diesel engine systems, such as EGR (Exhaust Gas Recirculation), fuel, air, DPF (Diesel Particulate Filter) DOC (Diesel Oxidation Catalyst) and SCR (Selective Catalytic Reduction) have very different dynamic response times. While fuel injectors response time (i.e. injection rate and timing) is of the order of milliseconds, the injection system rail pressure system response is of the order of half a second, the air and EGR systems respond tens of times slower than the rail pressure control system and after treatment systems, due to their remote locations respond hundred of times slower that the injection equipment. During transient operation of the engine, it is difficult to control engine emissions. There is a continuing need in the industry for a method to compensate engine setpoints during transient operation based upon a modeled system response to improve transient engine emissions to meet stringent Federal emissions guidelines and requirements.